The major objective of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) is to gather the data needed to estimate the prevalence and incidence of alcohol use disorders and their associated disabilities in the U.S. general population. This information will allow for the examination of the natural history of alcohol use disorders and their associated disabilities, identification of subgroups of the population at risk for these disabilities, refinement of etiologic hypotheses, and formation of the basis of rational and scientifically-based intervention and prevention programs. NESARC is a longitudinal survey with its first wave conducted in 2001-2002. The second wave entered the field in September 2004. The NESARC is a representative sample of the United States population, and 43,093 Americans participated in Wave 1. During Wave 2, an attempt to interview all 43,093 respondents will be made. The target population of the NESARC is the non-institutionalized population, 18 years and older, residing in the United States and the District of Columbia in households and selected group quarters. In Wave 3 of the NESARC, major consideration will be given to the collection of DNA. A public use database of the Wave 1 NESARC was disseminated to the research community in June 2004, and timely disposition of public use databases for subsequent NESARC waves also will follow. The major objectives of the Wave 1 and Wave 2 NESARC are: -to determine the prevalence, remission, chronicity and recurrence of alcohol and drug use disorders and their associated psychiatric and medical comorbidities; -to understand the relationships between alcohol and drug use disorders and other psychiatric and medical disorders over time; -to determine the number and characteristics of individuals receiving and in need of treatment for alcohol and drug use disorders and their associated disabilities; -to increase understanding of the interrelationships among individual and environmental factors, conditions and situations under which alcohol and violence are connected; -to determine the magnitude and extent of binge drinking among college-aged young adults and the adult population and to identify the characteristics of binge drinkers and risk factors influencing the initiation and remission of this hazardous drinking pattern; -to test competing etiologic models of comorbidity within a longitudinal context; -to conduct methodological and nosological research for the purpose of creating DSM-IV/ICD-11 research diagnostic criteria, as an adjunct to their clinical diagnostic criteria, for use in research areas (e.g., genetics, neuroscience) that have been hindered by existing clinical criteria; -to estimate the disease burden (DALYs and YLDs) attributable to alcohol, drug and mental disorders in the United States; and -to advance knowledge of the gene-environment interaction as it contributes to alcohol abuse and dependence and their associated medical and psychiatric comorbidities.